JPH02192440A - Production of cement clinker - Google Patents

Abstract

PURPOSE:To obtain a cement clinker having low cost using a slag produced as a by-product as a main raw material while carrying out effective utilization of retaining heat of the slug by adding and blending a cement clinker raw material in state retaining temperature of the slag to a specific value or above with the slag produced as a by-product in high-temperature state in a metal refining process and burning and cooling the resultant blend. CONSTITUTION:A cement clinker raw material is added and blended in state retaining temperature of slag to >=600 deg.C with a slag produced as a by-product in high-temperature state in a metal refining process and the resultant blend is burned and then cooled. As the above-mentioned slag, blast furnace produced as a by-product in iron refining process is preferably used. A lime raw material, silica raw material or iron oxide raw material is preferably used as the cement clinker raw material in using the blast furnace.

Description

[Detailed description of the invention] [Field of invention] The present invention relates to a method for manufacturing baked cement ingots.

More specifically, the present invention relates to a method for manufacturing baked cement ingots whose main raw material is slag, which is a by-product of a metal refining process.

[Background of the Invention] Generally, a calcined ingot (talinker) for producing Portland cement is made of calcareous raw material, silicic raw material, clay raw material, and iron oxide raw material, and Ca as a component of Portland cement.
060-66% by weight, S i 02 20-2s weight%, AiL2 o34-9% by weight, and Fe203
It is produced by mixing in a range of 2 to 5% by weight, firing the resulting mixture at a temperature of around 1450°C, and cooling it. By firing the above raw material at the above temperature, at least a part of the raw material becomes a molten state, and from the chemical components contained, 3CaO-Si0
2,2CaO-SiO2,3CaO-A 1203
, and 4CaO・,l! A crystalline cement mineral (hereinafter simply abbreviated as "cement mineral") mainly consisting of 203 .Fe2O is generated.

Portland cement is obtained by mixing the above-mentioned baked cement ingot with gypsum in a range of 3 to 5% by weight based on the obtained Portland cement, and pulverizing the mixture. The above-mentioned gypsum is added to adjust the solidification rate when Portland cement and water are kneaded.

It is known that blast furnace slag is used as part of the raw material for the above-mentioned baked ingots for producing Portland cement. Blast furnace slag is a byproduct of the pig iron manufacturing process, and is separated from pig iron in a high-temperature molten state. The above-mentioned blast furnace slag contains Ca0%S, which can constitute a part of the above-mentioned cement mineral.
It contains iO2, Al, and O as main components.

When blast furnace slag is used as part of the raw material for baked ingots for the manufacture of Portland cement (usually used in small amounts as an auxiliary raw material), it is usually obtained by cooling the blast furnace slag on a cooling bed and pulverizing it. Using slow-cooled slag or water-cooled granulated slag into small particles, the slag is added to other raw materials for cement ingots as necessary, and the chemical composition of the resulting Portland cement is made up of cement minerals with a cruising speed. After adjusting the ingredients so as to be within the range of production, the cement is processed into a baked cement ingot by firing and cooling in the same manner as the above-mentioned ordinary method for producing a baked cement ingot. In the above-described method for producing a baked cement ingot, slag is added to adjust the composition, and is remelted together with other raw materials by firing to produce the crystalline cement mineral. By the above manufacturing method,
By effectively utilizing the above-mentioned chemical components contained in blast furnace slag, a baked ingot for producing Portland cement can be obtained.

Incidentally, blast furnace slag is water-cooled to form granulated slag, which is then dried and crushed to form granulated slag powder, which may also be used directly as a component of other cements such as blast furnace cement.

Cement is a substance that is consumed in large quantities in fields such as civil engineering and construction, and it is desirable to keep the cost low.

In the field of cement industry, it is important to obtain large quantities of raw materials at low cost, and to reduce fuel costs by effectively utilizing heat, since a huge amount of heat is required to sinter the raw materials.

Therefore, in the production of baked ingots for the production of Portland cement, it is desired to develop a production method that uses blast furnace slag, which is produced in large amounts as a by-product in the metal refining process, as the main raw material and that can also effectively utilize the heat contained in the blast furnace slag. .

[Objective of the Invention] The object of the present invention is to use slag as a by-product in the metal refining process as the main raw material, and to effectively utilize the heat of the blast furnace slag to produce cement ingots for the production of Portland cement. The objective is to provide an improved method for

[Summary of the Invention] The present inventor has discovered that in the conventionally known production method in which blast furnace slag is used as a part of the raw material for the baked ingots for producing Portland cement, the slag in a high-temperature molten state is once cooled. , focused on the fact that slag is mixed with other cement raw materials and then fired again at a high temperature, which is disadvantageous in terms of effective use of heat. After thinking about it, I arrived at the present invention.

The present invention processes slag produced as a by-product in a high-temperature state during a metal refining process while maintaining the temperature of the slag at 600°C or higher.
The present invention provides a method for producing a baked cement ingot, which comprises adding raw materials for the baked cement ingot, mixing them, baking the resulting mixture, and then cooling the mixture.

Next, preferred embodiments of the present invention will be shown.

(1) The above-mentioned slag is blast furnace slag that is a by-product in the iron manufacturing process.

(2) The slag is a slag that has been desulfurized in advance.

(3) Sprinkling the slag with a high-speed fluid to granulate it, and mixing the slag in the form of granules with the cement sintered ingot raw material.

(4) The cement baked ingot raw material is a calcareous raw material, a silicate raw material, and an iron oxide raw material.

(5) The cement sintered ingot raw material is in the form of powder and granules, and is in a preheated state before being mixed with the slag.

(6) The above firing is performed at a temperature range of 900 to 1700℃ for 5 minutes.
Do this for ~60 minutes.

(7) The above-mentioned firing is carried out in an air flow with an oxygen partial pressure of 0.1 to 100 Torr using a rotary kiln equipped with a suspension preheater.

[Effects of the Invention] In the manufacturing method of the present invention, blast furnace slag in a high temperature state is mixed with powder and granules of other cement sintered ingot raw materials and fired without excessively cooling the blast furnace slag, which improves the effectiveness of heat in cement manufacturing. Usage can be improved. Further, in the manufacturing method of the present invention, it is possible to make maximum use of cheap blast furnace slag, which is produced as a by-product in large amounts in the metal refining process, and therefore, cement manufacturing costs can be reduced.

In addition, blast furnace slag containing sulfur components (sulfides) can be removed to facilitate firing and improve quality, and the recovered sulfur oxides can be converted into gypsum, which can be used as a raw material for cement addition. can do.

[Detailed Description of the Invention] The method for producing a cement baked ingot of the present invention is to reduce the temperature of the slag by-produced in a high-temperature state during a metal refining process to 600°C.
Cement sintered ingot raw materials are added and mixed while the temperature is maintained at .degree. C. or higher, preferably 900.degree. C. to 1500.degree. C., and the resulting mixture is fired, followed by cooling.

The slag produced as a by-product in the metal refining process mentioned above may be any slag that contains chemical components that make up cement minerals. ) can be used, but blast furnace slag, which is produced as a by-product in the ironmaking process of iron manufacturing, is particularly preferred. In the above pig iron making process, limestone is generally used as a solvent for iron ore when producing pig iron in a blast furnace. By charging iron ore, coke, and limestone from the top of the blast furnace and heating them, materials that are easily reduced, mainly iron, are obtained as pig iron, and other materials that are difficult to be reduced are obtained as slag. Since the above blast furnace slag contains Cab, 5in2, and AJ2203 as main components, it can be advantageously used as a raw material for baked ingots for producing Portland cement by adding other cement baked ingot raw materials to adjust the ingredients. be able to. In the above pig iron making process, separation of slag and pig iron can be easily carried out in a molten state by taking advantage of the fact that the specific gravity of slag is lower than that of pig iron.

In the method of the present invention, the blast furnace slag, which is in a high-temperature molten state and is produced as a by-product in the above-mentioned ironmaking process, is not excessively cooled.
It is necessary to add and mix the cement baked ingot raw material while maintaining the temperature at 600° C. or higher.

After separating the blast furnace slag from the pig iron, other than natural cooling due to contact with the atmosphere, the blast furnace slag shall be specially treated for cooling as employed in the production of granulated slag or slowly cooled slag. It is preferable to maintain the high temperature state as much as possible. By mixing it with other cement sintered ingot raw materials at the above-mentioned high temperature state, the cement sintered ingot can be fired advantageously without wasting the thermal energy of the molten blast furnace slag.

The reaction for producing cement minerals in cement firing is a solid phase reaction, and usually occurs at a temperature range of about 600° C. or higher. Therefore, if other cement sintered ingot raw materials are added and mixed with the blast furnace slag cooled to a temperature below 600°C, thermal energy will be required to supplement the cooling during the above-mentioned sintering, and the amount of heat for sintering will increase. Therefore, it is not desirable.

The addition of other cement baked ingot raw materials to the blast furnace slag may be carried out while the blast furnace slag is in a liquid state, but it is preferable to add the other cement ingot raw materials in the form of granules, since they can be mixed advantageously in the form of granules. is preferred. The above addition,
The mixing operation can be advantageously carried out by scattering the above-mentioned blast furnace slag with a high-speed fluid having a speed in the range of 10 to 1000 m/sec and granulating it into a granular state. As a device for scattering blast furnace slag with the above-mentioned high-speed fluid, for example, a conventionally known device for blowing granulated slag, etc. can be used.

The above-mentioned blast furnace slag is preferably desulfurized before being mixed with the above-mentioned other cement sintered ingot raw materials. As mentioned above, the blast furnace slag contains Cab, Sin, and Al1. O, as a main component, but also contains trace components such as sulfur, phosphorus, and arsenic, which are undesirable if left in the cement ingot. When a cement baked ingot is manufactured using blast furnace slag containing the above trace components, compounds derived from the trace components, especially compounds such as gypsum produced from sulfur, are fused in the kiln during the firing process described below.
Operations may become difficult.

The above-mentioned trace components can be removed by a conventionally known method, for example, by circulating an oxygen-containing gas from the bottom of a container containing molten blast furnace slag, and bringing the trace components vaporized along with the gas into contact with a recovery agent or an absorbent. This can be done by using a method of removing the particles by removing the particles.

Other cement baked ingot raw materials that can be added to blast furnace slag to adjust the composition include calcareous raw materials such as limestone, chalk, and marl; silicic raw materials such as chert, soft silica stone, silica sand, and sandstone; clay, shale, Examples include clayey raw materials such as mudstone, slate, and loam; and iron oxide raw materials such as iron ore, iron mackerel, and copper. Fluorite may be further added as the cement sintered ingot raw material. Fluorite acts as a solvent for the cement sintered ingot raw material, and 3CaO・S i
It has the effect of promoting the formation of 02 and lowering the firing temperature.

Among the above-mentioned raw materials, calcareous raw materials, silicic raw materials, and iron oxide raw materials are particularly preferred as components to be added to blast furnace slag. This is because blast furnace slag tends to lack calcareous, silicic, and iron oxide components. The blending ratio of blast furnace slag and the above-mentioned raw materials can be arbitrarily determined depending on the characteristics of the target cement, and the blending ratio of each raw material is determined by the hydraulic ratio () 1. M), silicic acid rate (S, M),
It may be calculated by a conventionally known method from the component ratios such as the iron base (1, M) and the activity coefficient (A, I).

It is preferable that the cement sintered ingot raw material is pulverized before being added to the blast furnace slag in order to perform mixing advantageously, and it is preferable that the cement sintered ingot raw material be preheated in order to effectively utilize heat and increase thermal efficiency. . The above preheating may be performed in the same manner as in the conventionally known method for manufacturing cement baked ingots, using a rotary kiln equipped with a suspension preheater (S
It is preferable to use a rotary kiln (NS P kiln) with a part of its preheater.The above kiln is preferably a rotary kiln (NS
P kiln) is preferred. By using the above-mentioned apparatus, the cement sintered ingot raw material is usually 800 to 800
It is preheated to about 900°C.

Then, adding a cement baked ingot raw material to the blast furnace slag,
Mix. The addition is preferably carried out at the inlet of the rotary kiln.

The method for producing a baked cement ingot according to the present invention will be explained in more detail as an embodiment using the apparatus (rotary kiln) shown in FIG. 1 of the attached drawings and its attached apparatus.

The blast furnace slag is blown away by high-speed fluid by the blowing device 1 shown in FIG. 1, and blown into the mixing tank 2 in the form of granules. Further, other cement baked ingot raw materials are pulverized and preheated in the preheater part 3, and then added to and mixed with the blast furnace slag in the form of granules in the mixing tank 2. The preheater part 3 consists of cyclones 4 stacked in four stages, and the cement sintered ingot raw material is gradually lowered from the upper cyclone to the lower stage by the residual heat of the rotary kiln 5 and the heat supplied from the calcining furnace 6. Preheated.

The blast furnace slag and other cement baked ingot raw materials mixed in the mixing tank 2 are transferred to the rotary kiln 5 by the charger 7.
and fired. The rotary kiln 5 is heated by combustion gas supplied by a burner 8. The above combustion gas usually has a temperature of 1800 to 2000.
℃ and an oxygen partial pressure in the range of 0.1 to 100 torr. The above baking is performed at a temperature range of 900-1700°C, preferably 1400-1500°C for 5-60 minutes.
It is preferably carried out for 10 to 30 minutes. When the firing conditions are out of the above range, the desired cement mineral may not be obtained, or the sintering may proceed excessively, making it difficult to crush the resulting baked ingot.

By performing firing under the above-mentioned conditions, the blast furnace slag and the cement sintered ingot raw material react in a semi-molten state to produce cement minerals. The cement mineral is discharged from the rotary kiln 5 and cooled by a cooling device 9 to obtain a baked cement ingot. As the cooling device, for example, a conventionally known device such as an air quenching cooler can be used.

Portland cement can be produced by further adding gypsum to the baked cement ingot obtained by the above production method and pulverizing it.

Next, examples of the present invention will be shown.

[Example 1] Molten blast furnace slag separated from the ironmaking process of iron manufacturing is once received in a ladle car, and an oxygen partial pressure of 104 to t is applied from the bottom of the ladle car.
Gas at o-' atmospheric pressure was introduced into the blast furnace slag to oxidize sulfides and desulfurize them. The blast furnace slag subjected to the above desulfurization treatment contained 1.4% by weight of CaO4, 34.6% by weight of Sin, and 0.314.1% by weight of A1□.

Note that 43 kg of gypsum was recovered from S02 contained in the exhaust gas for each ton of blast furnace slag.

Cement baked ingots were produced from the above-mentioned treated blast furnace slag and other raw materials for cement baked ingots by the following method using the rotary kiln and attached equipment shown in FIG.

First, the above-mentioned blast furnace slag is charged from the pot truck to the blowing device 1 attached to the mixing tank 2 at the entrance of the rotary kiln.
The blast furnace slag was made into a granular state using steam having a velocity of m/sec, and was scattered into the mixing tank 2. The temperature of the blast furnace slag was 1200°C. At the same time, the cement sintered ingot raw material powder preheated in the preheater part 3 at the upper part of the rotary kiln was supplied to the mixing tank 2, and added to and mixed with the granulated blast furnace slag. As the above-mentioned cement baked ingot raw materials, 2.75 tons of limestone, 0.25 tons of silica stone, and 0.075 tons of iron ore were added to 1 ton of blast furnace slag.

Next, the above-mentioned mixture of blast furnace slag, limestone, silica stone and iron ore is transferred to the rotary kiln 5 by the charger 7.
and fired. In the above firing, a flame is created using heavy oil as fuel using burner 8, and the oxygen partial pressure of the combustion gas is 5.
An air flow of 0 torr is passed through the rotary kiln 5, and the temperature distribution of the raw material in the rotary kiln 5 is t ooo ℃~
The test was carried out by heating to 1500° C. for 30 minutes.

The fired product (cement mineral) obtained in the above-described operation was cooled in a cooling device 9 provided continuously to the rotary kiln 5 to obtain 2.86 tons of fired ingots for producing Portland cement.

The amount of heat required to produce the above-mentioned cement ingot was 625,000 kilocalories per ton of the ingot.

Portland cement using the above-mentioned baked cement ingot is
As a result of the test specified in JIS R5201, the mortar compressive strength was 388 kg f/c rn" (28
day).

[Comparative Example 1] An air-cooled slag was produced from the blast furnace slag used in Example 1 according to a conventional method.

The same amounts of limestone, silica stone, and iron ore powder as in Example 1 were added to 1 ton of the above slowly cooled slag and mixed. The above mixture was charged into a part of the preheater of the same rotary kiln used in Example 1 to preheat it, and then directly supplied to the rotary kiln without being mixed with the blast furnace slag powder in the mixing tank. By firing under the firing conditions and subsequently cooling, a fired ingot for producing Portland cement was obtained. During the above-mentioned firing, sulfate was observed to adhere to the bottom of the kiln, making long-term operation difficult.

The amount of heat required to produce the above-mentioned baked ingot was 666,000 kilocalories per ton of the baked ingot.

In addition, the baked cement ingot obtained above has a high content of sulfur oxides (So, 0.96%) and is inferior in quality.
As a result of the test specified in IS R5201, the mortar compressive strength was 321 kgf/Cgo (28 days).

[Evaluation of the amount of heat required] The amount of heat required to produce a normal cement ingot is approximately 80
It's 10,000 kilocalories. Therefore, by using blast furnace slag as the main raw material, the required amount of heat can be significantly reduced compared to the current cement firing method, and by using the production method of the present invention, the required amount of heat can be further reduced. .

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of an embodiment of a rotary kiln and its auxiliary equipment used in the present invention. 1: Blast furnace slag blowing device, 2: Mixing tank, 3: Part of breheater, 4: Cyclone, 5: Rotary kiln, 6: Calciner, 7: Charger 8: Burner 9: Cooling device. Patent applicant Representative of Ube Industries Co., Ltd. Patent attorney Yasuo Yanagawa

Claims (1)

[Claims] 1. Slag produced as a by-product at high temperatures in the metal refining process is maintained at a temperature of 600°C or higher, and cement sintered ingot raw materials are added and mixed, the resulting mixture is fired, and then cooled. A method for producing a baked cement ingot, characterized by the following.